Cutting Tool With Insert Having A Tapered Bottom

ABSTRACT

A cutting tool for use in impinging earth strata includes a cutting tool body that contains a socket at an axial forward end thereof and an insert structured and arranged for being affixed to the cutting tool body within the socket. The insert includes a mounting end portion at an axial rearward end of the insert. The mounting end portion includes a first tapered segment, a second tapered segment adjacent and axially rearward of the first tapered segment wherein the second tapered segment has an axial rearward end diameter, and a base adjacent and axially rearward of the second tapered segment, the base having a base diameter that is greater than the axial rearward end diameter of the second tapered segment. The socket is structured and arranged for cooperating with the mounting end portion of the insert.

BACKGROUND OF THE INVENTION

The present invention relates to cutting tools for impinging a substrate in, for example, a mining or construction activity.

Cutting tools are used in conjunction with a machine used to break up (or cut) a substrate such as coal, rock, asphalt pavement, asphaltic concrete, concrete or the like. In its very basic aspects, such a machine includes a driven member (e.g., a chain, a wheel or a drum), a holder either directly or indirectly mounted to the driven member, and a rotatable cutting tool rotatably held in the holder. Typically, the cutting tool has a hard (e.g., cemented [cobalt] tungsten carbide) insert at the axial forward end thereof and is rotatably retained by the tool holder. It is the cutting tool and, more particularly the hard insert that impinges the substrate so as to break it into pieces upon impact.

Because of the severe operating environment, the hard insert, as well as the entire rotatable cutting tool, is subjected to great forces. These forces can destroy the cutting tool and/or the hard insert if they do not possess adequate strength and fracture toughness. Thus, it would be desirable if the design of the cutting tool and/or the hard insert would enhance the strength and fracture toughness thereof.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a cutting tool for use in impinging earth strata includes a cutting tool body with a central longitudinal axis and has a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end. The cutting tool body contains a socket at the axial forward end thereof. The cutting tool further includes an insert structured and arranged for being affixed to the cutting tool body within the socket, the insert having the same central longitudinal axis as the cutting tool body. The insert includes a generally conical tip portion at an axial forward end of the insert, a central portion adjacent and axially rearward of the generally conical tip portion and a mounting end portion at an axial rearward end of the insert wherein the mounting end portion is adjacent and axially rearward of the central portion. The mounting end portion includes a first tapered segment adjacent and axially rearward of the central portion, a second tapered segment adjacent and axially rearward of the first tapered segment wherein the second tapered segment has an axial rearward end diameter, and a base adjacent and axially rearward of the second tapered segment, the base having a base diameter that is greater than the axial rearward end diameter of the second tapered segment.

In accordance with another aspect of the invention, a cutting tool insert having a central longitudinal axis includes a generally conical tip portion at an axial forward end of the insert, a central portion adjacent and axially rearward of the generally conical tip portion and a mounting end portion at an axial rearward end of the insert wherein the mounting end portion is adjacent and axially rearward of the central portion. The mounting end portion includes a first tapered segment adjacent and axially rearward of the central portion, a second tapered segment adjacent and axially rearward of the first tapered segment wherein the second tapered segment has an axial rearward end diameter, and a base adjacent and axially rearward of the second tapered segment, the base having a base diameter that is greater than the axial rearward end diameter of the second tapered segment.

In accordance with yet another aspect of the invention, a cutting tool body with a central longitudinal axis includes a head portion at an axial forward end of the cutting tool body, the head portion having a socket that defines an opening at the axial forward end. The cutting tool body also includes a collar portion axially rearward of the head portion and a shank portion axially rearward of the collar portion at an axial rearward end. The socket includes a first tapered wall adjacent and axially rearward of the opening, a second tapered wall adjacent and axially rearward of the first tapered wall, and a base portion adjacent and axially rearward of the second tapered wall.

These and other aspects of the present invention will be more fully understood following a review of this specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional side view of a cutting tool, in accordance with an aspect of the invention.

FIG. 2 is an enlarged side view of the cutting tool insert shown in FIG. 1, in accordance with an aspect of the invention.

FIG. 3 is a partial sectional side view of the cutting tool body shown in FIG. 1, in accordance with an aspect of the invention.

DETAILED DESCRIPTION

Referring to the drawings, there is illustrated a cutting tool of the invention, generally designated as 10. Exemplary cutting operations for the cutting tool 10 include, without limitation, road planing (or milling), coal mining, concrete cutting, and other kinds of cutting operations wherein a cutting tool with a hard cutting member impinges against a substrate (e.g., earth strata, pavement, asphaltic highway material, concrete, and the like) breaking the substrate into pieces of a variety of. In addition, it will be appreciated that the cutting tool 10 of the invention may be manufactured in various sizes and dimensions depending upon the desired application of the tool.

As used herein, the term “cutting tool” generally refers to rotatable cutting tools or indexable cutting tools that are generally fixed in place during use.

Referring to FIG. 1, cutting tool 10 has a central longitudinal axis A-A. In one aspect, cutting tool 10 may be symmetrical about and/or rotate about the axis A-A. Cutting tool 10 includes an elongate cutting tool body, generally designated as 12, which typically is made of steel. Elongate cutting tool body 12 presents a generally cylindrical geometry, and has an axial forward end 14 and an axial rearward end 16.

Elongate cutting tool body 12 includes a head portion 18, a shank portion 20 and a collar portion 22 wherein the collar portion 22 is mediate of and contiguous with the head portion 18 and the collar portion 22. The collar portion 22 is axially rearward of the head portion 18 and the shank portion 20 is axially rearward of the collar portion 22. The shank portion 20 includes an annular groove 24 adjacent the axial rearward end 16 for receiving a retainer ring (not shown), as is generally known.

As shown in FIG. 3, the head portion 18 contains a socket 28 at the axial forward end 14 of the cutting tool body 12. The socket defines an opening 30 at the axial forward end 14 of the cutting tool body 12. In one aspect, the socket 28 includes a first tapered wall 32 adjacent and axially rearward of the opening 30, a second tapered wall 34 adjacent and axially rearward of the first tapered wall 32, and a base portion 36 adjacent and axially rearward of the second tapered wall 34.

The second tapered wall 34 of the socket 28 has an axial rearward diameter D1, i.e. the diameter at the most axially rearward portion of the second tapered wall 34 where the second tapered wall 34 meets the base portion 36. The base portion 36 of the socket 28 has a base portion diameter, e.g. D2. In one aspect, the base portion diameter D2 is greater than the axial rearward diameter D1.

Still referring to FIG. 3, the first tapered wall 32 of the socket 28 tapers generally inwardly toward the axial rearward end 16 of the cutting tool body 12. In one aspect, the first tapered wall 32 tapers at a first angle W from the central longitudinal axis A-A. The second tapered wall 34 of the socket 28 tapers generally inwardly toward the axial rearward end 16 of the cutting tool body 12. In one aspect, the second tapered wall 34 tapers at a second angle X from the central longitudinal axis A-A. In another aspect, the first angle W of the first tapered wall 32 is different from the second angle X of the second tapered wall 34.

Referring to FIGS. 1 and 2, the cutting tool 10 further includes a hard cutting member or hard cutting insert, generally designated as 40. The insert 40 is structured and arranged for being affixed by, for example, brazing within the socket 28 at the axial forward end 14 of the cutting tool body 12. When affixed to the cutting tool body 12, the insert has essentially the same central longitudinal axis A-A as the cutting tool body 12.

Referring particularly to FIG. 2, the insert 40 includes an axial forward end 42 and an axial rearward end 44. Insert 40 may be made from, for example, a hard material such as, for example, cemented (cobalt) tungsten carbide. The insert 40 includes a generally conical tip portion 46 at or adjacent the axial forward end 42 of the insert 40, a central portion 48 adjacent to and axially rearward of the generally conical tip portion 46 and a mounting end portion 50 at the axial rearward end 44 of the insert 40. The mounting end portion 50 is adjacent and axially rearward of the central portion 48.

In one aspect, the mounting end portion 50 of the insert 40 includes a first tapered segment 52 adjacent to and axially rearward of the central portion 48, a second tapered segment 54 adjacent to and axially rearward of the first tapered segment 52 and a base 56 adjacent to and axially rearward of the second tapered segment 54.

As shown in FIG. 2, the second tapered segment 54 has an axial rearward end diameter D3, i.e. the diameter at the most axially rearward portion of the second tapered segment 54 where the second tapered segment 54 meets the base 56. The base 56 has a base diameter, e.g. D4. In one aspect, the base diameter D4 is greater than the axial rearward end diameter D3 of the second tapered segment 54.

Still referring to FIG. 2, the first tapered segment 52 of the insert 40 tapers generally inwardly toward the axial rearward end 44 of the insert 40. In one aspect, the first tapered segment 52 tapers at a first angle Y from the central longitudinal axis A-A. The second tapered segment 54 of the insert 40 tapers generally inwardly toward the axial rearward end 44 of the insert 40. In one aspect, the second tapered segment 54 tapers at a second angle Z from the central longitudinal axis A-A. In another aspect, the first angle Y of the first tapered segment 52 is different from the second angle Z of the second tapered segment 54.

FIG. 1 illustrates the insert 40 as positioned or affixed in place in the socket 28 of the cutting tool body 12. As will be appreciated, the first tapered wall 32 of the socket 28 is structured and arranged for cooperating with the first tapered segment 52 of the insert 40. In addition, the second tapered wall 34 of the socket 28 is structured and arranged for cooperating with the second tapered segment 54 of the insert 40. Also, the base portion 36 of the socket 28 is structured and arranged for cooperating with the base 56 of the insert 40. In addition, it will be appreciated that the base 56 of the insert 40 and the base portion 36 of the socket 28 are structured and arranged to have sufficient dimensional tolerances so that the base 56 of the insert 40 can be inserted into the base portion 36 of the socket 28.

During operation of the cutting tool 10, it will be appreciated that forces are generated at the axial forward end 42 of the insert 40 and that these forces are transferred through the insert body, i.e. through the conical tip portion 46 and the central portion 48 and through the mounting end portion 50 creating a resulting stress on the base 56 of the insert 40. Advantageously, the design of the first tapered segment 52 and, in particular, the second tapered segment 54 results in less material being removed from the socket 28 which in turn strengthens the surrounding steel material of the head portion 18 of the cutting tool body 12 which supports the insert 40 thus reducing the possibility of the insert 40 fracturing and/or reducing the possibility of steel fatigue in the head portion 18 of the cutting tool body 12 so as to prevent catastrophic failure of the cutting tool 10.

In addition, it will be appreciated that the base portion 36 of the socket 28 in association with the base 56 and the tapered segments 52 and 54 are structured and arranged to allow additional brazing material to flow and form around the insert 40 mounting end portion 50 resulting in a stronger bonding between the insert 40 and the socket 28.

It will also be appreciated that the base 56 is structured and arranged to provide added material to the insert 40 at a location where maximum equivalent loading occurs during the impact cycle of the cutting tool 10 and to provide longer lasting wear protection to the cutting tool body 18 as the tool reaches its final life cycle under abrasive cutting conditions.

Whereas particular aspects of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention. 

1. A cutting tool for use in impinging earth strata, the cutting tool comprising: a cutting tool body with a central longitudinal axis and having a head portion at an axial forward end, a collar portion axially rearward of the head portion, and a shank portion axially rearward of the collar portion at an axial rearward end, the cutting tool body containing a socket at the axial forward end thereof; and an insert structured and arranged for being affixed to the cutting tool body within the socket, the insert having the same central longitudinal axis as the cutting tool body, the insert comprising a generally conical tip portion at an axial forward end of the insert, a central portion adjacent and axially rearward of the generally conical tip portion and a mounting end portion at an axial rearward end of the insert, the mounting end portion adjacent and axially rearward of the central portion, the mounting end portion comprising: a first tapered segment adjacent and axially rearward of the central portion; a second tapered segment adjacent and axially rearward of the first tapered segment, the second tapered segment having an axial rearward end diameter; and a base adjacent and axially rearward of the second tapered segment, the base having a base diameter that is greater than the axial rearward end diameter of the second tapered segment.
 2. The cutting tool of claim 1, wherein the first tapered segment of the insert tapers inwardly toward the axial rearward end of the insert.
 3. The cutting tool of claim 2, wherein the second tapered segment of the insert tapers inwardly toward the axial rearward end of the insert.
 4. The cutting tool of claim 1, wherein the first tapered segment of the insert tapers at a first angle from the central longitudinal axis.
 5. The cutting tool of claim 4, wherein the second tapered segment of the insert tapers at a second angle from the central longitudinal axis, wherein the first angle of the first tapered segment is different from the second angle of the second tapered segment.
 6. The cutting tool of claim 1, wherein the socket defines an opening at the axial forward end of the cutting tool body and the socket comprises: a first tapered wall adjacent and axially rearward of the opening; a second tapered wall adjacent and axially rearward of the first tapered wall; and a base portion adjacent and axially rearward of the second tapered wall.
 7. The cutting tool of claim 6, wherein the first tapered wall of the socket is structured and arranged for cooperating with the first tapered segment of the insert.
 8. The cutting tool of claim 7, wherein the second tapered wall of the socket is structured and arranged for cooperating with the second tapered segment of the insert.
 9. The cutting tool of claim 8, wherein the base portion of the socket is structured and arranged for cooperating with the base of the insert.
 10. The cutting tool of claim 8, wherein the second tapered wall of the socket has an axial rearward end diameter and the base portion of the socket has a base portion diameter that is greater than the axial rearward end diameter of the second tapered wall.
 11. The cutting tool of claim 6, wherein the first tapered wall of the socket tapers at a first angle from the central longitudinal axis.
 12. The cutting tool of claim 11, wherein the second tapered wall of the socket tapers at a second angle from the central longitudinal axis, wherein the first angle of the first tapered wall is different from the second angle of the second tapered wall.
 13. A cutting tool insert having a central longitudinal axis, the cutting tool insert comprising: a generally conical tip portion at an axial forward end of the cutting tool insert; a central portion adjacent and axially rearward of the generally conical tip portion; a mounting end portion at an axial rearward end of the cutting tool insert, the mounting end portion adjacent and axially rearward of the central portion, the mounting end portion comprising: a first tapered segment adjacent and axially rearward of the central portion; a second tapered segment adjacent and axially rearward of the first tapered segment, the second tapered segment having an axial rearward end diameter; and a base adjacent and axially rearward of the second tapered segment, the base having a base diameter that is greater than the axial rearward end diameter of the second tapered segment.
 14. The cutting tool insert of claim 13, wherein the first tapered segment tapers inwardly toward the axial rearward end of the cutting tool insert.
 15. The cutting tool insert of claim 14, wherein the second tapered segment tapers inwardly toward the axial rearward end of the cutting tool insert.
 16. The cutting tool insert of claim 13, wherein the first tapered segment tapers at a first angle from the central longitudinal axis of the cutting tool insert.
 17. The cutting tool insert of claim 16, wherein the second tapered segment tapers at a second angle from the central longitudinal axis of the cutting tool insert, wherein the first angle of the first tapered segment is different from the second angle of the second tapered segment.
 18. A cutting tool body with a central longitudinal axis, the cutting tool body comprising: a head portion at an axial forward end of the cutting tool body, the head portion having a socket that defines an opening at the axial forward end; a collar portion axially rearward of the head portion; and a shank portion axially rearward of the collar portion at an axial rearward end, wherein the socket comprises: a first tapered wall adjacent and axially rearward of the opening; a second tapered wall adjacent and axially rearward of the first tapered wall; and a base portion adjacent and axially rearward of the second tapered wall.
 19. The cutting tool body of claim 18, wherein the second tapered wall of the socket has an axial rearward end diameter and the base portion of the socket has a base portion diameter that is greater than the axial rearward end diameter of the second tapered wall.
 20. The cutting tool body of claim 18, wherein the first tapered wall of the socket tapers at a first angle from the central longitudinal axis and the second tapered wall of the socket tapers at a second angle from the central longitudinal axis, the first angle of the first tapered wall being different from the second angle of the second tapered wall. 